How strong are Klingons?

Talking about physical strength. Seems humans can hold their own against them when humans are the more passive types and don't do daily hand to hand combat training for boarding which Klingons prize in (warrior caste and all).

I remember in the DS9 episode "Take me out to the Holosuite", Sisko says that Worf is stronger than a Vulcan. Previously stated in the episode is the fact that a Vulcan is 3 times stronger than a human.

In S1E9 of the new ST, we see skinny Michael hold her own against the taller Klingon guy (forgot his name).